Svetlana Kuznetsova

Serena uncertain for Australia

Williams was around two months pregnant when she captured her 23rd grand slam singles title in Melbourne earlier this year and was hoping to defend her crown next January following the birth of her daughter in September.

"Serena is getting ready for 2018," the 36-year-old American's coach Patrick Mouratoglou told CNN. "She is practising and getting back in shape. I will be joining her soon in Florida.

"We will see how her body is reacting and how her tennis level is and we will take a decision regarding Australia."